As described in the Patent Document 1, for instance, in an ultrasonic imaging apparatus used for medical imaging diagnosis, there is known a method which estimates a distribution of modulus of elasticity of tissue, based on a change amount within a small area in a diagnostic moving image (a B-mode image), and converts stiffness into a color map for display. However, byway of example, in the case of a peripheral zone of a tumor, neither acoustic impedance nor the modulus of elasticity may show a major difference, relative to the surrounding tissue. In this case, it is not possible to figure out a boundary between the tumor and the surrounding tissue, in the diagnostic moving image nor in the elasticity image.
The technique described in the Patent Document 2 suggests a method which generates a scalar field image directly from motion vectors of a diagnostic moving image, thereby allowing a tissue boundary to be discerned, when neither the acoustic impedance nor the modulus of elasticity are largely different relative to the surroundings.